Many patients with systolic dysfunction undergo elective percutaneous coronary intervention (PCI) despite the unknown risk and limited data supporting its use. Therefore, the aim of this study was to evaluate the association between the severity of left ventricular (LV) systolic dysfunction and hospital mortality in patients who undergo elective PCI. A retrospective cohort study was conducted of all patients who underwent elective PCI in New York State in 1998 and 1999. Patients were stratified into 5 groups on the basis of their LV ejection fractions (EFs) before PCI (>55%, 46% to 55%, 36% to 45%, 26% to 35%, and < or =25%). Comparisons of demographic, procedural, and outcome variables were performed, and adjusted odds ratios (ORs) were calculated to evaluate the relation between the EF and hospital mortality. Among 55,709 patients who underwent elective PCI, EFs < or =25%, 26% to 35% and 36% to 45% were present in 3.4%, 7.6%, and 17.4%, respectively. Hospital mortality was 0.3%, 0.2%, 0.6%, 1.2%, and 2.7% in the groups with EFs >55%, 46% to 55%, 36% to 45%, 26% to 35%, and < or =25%, respectively (p <0.001). After multivariate adjustment, an increased risk for hospital mortality was significant for EF groups of 36% to 45% (OR 1.56, 95% confidence interval 1.06 to 2.30), 26% to 35% (OR 2.17, 95% confidence interval 1.42 to 3.31), and < or =25% (OR 3.85, 95% confidence interval 2.46 to 6.01) compared with EF >55%, respectively. In conclusion, this analysis demonstrates that elective PCI is commonly performed in patients with reduced EFs, and the risk for hospital mortality increases as the EF decreases. For patients who undergo elective PCI, an EF < or =45% is associated with higher adjusted hospital mortality. Whether elective PCI in patients with low EFs reduces morbidity and/or mortality over medical therapy alone is unknown.